Impulse coupling



N 25, 1924. 1,517,203 R. K. EVANS I IMPULSE COUPLING Filed Nov. 8. 192; 2 Shees-Sheet 1 [Til/EH20? R. K. EVANS IMPULSE. COUPLING Filed Nbv. a. 1921 2 Sheets-Sheet 2 HEE'SQ MW Patented Nov. 25, 1924.

"UNITED STATES 4 Y 1 03 PATENT. OFFICE.

noNADD x. nvA s, or ANDnRso-N, INDIANA, ASSIGNOR T nnmvntncrnrc com-ANY, on A nnsoN, INDI A, .A CORPORATION or INDIANA.

- IFIZEULSE oo'UPnINe.

Application filed HovemberS, 1921. Serial No. 513,809. b

Po ell whom it comer n:

Be it known that I, RONALD K. EVANS, a

citizen of the United States of America, re}.

themagneto, and operating normally to ar-' rest the movement of the magneto armature and then to give to the magneto armature a sudden quick turningmovement to produce the maximum current flow for ignition purposes and'at the. proper time forignition.

' The speed of this impulse or sudden move-' ment'of the armature is generally independent of the speed of the magneto operat ng mechanism, and is accomplished by means of aspring which is wound up or otherwise strained during the time when the-armature is restrained from moving; this spring being automatically released at the proper time, for

ignition. Thus animpulsesuflici'ent for ig- 'nition purposes may be imparted to the armaturealthough the speed of the magneto operating mechanism maybe too slow for lgnition purposes. Suchan impulse dev1ce-'1s therefore particularly useful for automobiles in which magneto ignition isemployed, and

- where the engine which. drives the vehicle and also-the magneto is started by hand or by othe'rdevice operating. at too slow a speed A 'to operate the magneto to produce ignition by themagneto.

: Devices of this sort have been produced wherein the impulse spring acts also as a.

shock absorbing spring to assist intaking up the shock which would come upon the arma-' ture duev to the operation of. the impulse mechanism. A device of thisjkind 1s de: scribed in the patent to H. O. Putt, No,

" 1,326,529, patented December 30, 1919. -Thisdevice employs 'a helical coil spring1.a's an impulsea'nd shock 'absorbing'or cus ionmg spring.

-Wh'le springs of the clock orin volute type 4 have been used as impulse springs for. im-

pulse devices, so far as Iam aware, e'volute spring has not been used both asan{impulse spring and as. a cushioning spring It is therefore among theT'principallobjects" oi the, present in ention: to provide an 5+5 of Fig. 4; and

pulse device for 'magneto s' wherein an involute spring functions both as the impulse spring and as the cushioning spring.

Other and'further objects of the present I invention will be apparent from the following description, reference being had to the accompanying drawings, wherein a preferred embodiment of the present invention is clearly shown.

In the form of my 'invention shown herein, the new spring arrangement is shown in Fig. 2 is an elevation of the samewiththe v rotatabledriving member removed, showing thefixed cam member, and showing in dotted lines the relativelocationof the circular driva ing, pawl carrying member in one posit on;

- Fig; 3 is a view lookingat the. inside of 1 A the removed, rotating driving member, showing in dotted lines the relative location of the fixed cam; the view being taken onthe plane indicated by thedotted line 3.3 of Fig. i;

' Fig. 4 is a' sectionalview taken on the plane indicated by line 4 4.of. Fig. 1-;

Fig. 5 is a-sectional view taken on line Y Fig. 6 is a sectionalview takengon line e--e of Fig. 4.

Referring "to that embodiment of my in "9,5, 'ings, the casing A of the magneto containsv vention shown in the accompanying drawthe usual horse-shoe magnets, armature, and

the like, not shown, and a journal bearing- ..a for the armature or magneto shaft B.

The shaft B'jis preferably provided with a tapered ortion b and a threaded end por- Qnf"b.. is a drive shaft connected by. suitable coupling D with the coupling D,

the latter bemgsecured to or integral with a rotatable drivingmember 10 A stationary part 1 is provided with an outwardly projeeting fi'ange 2, and is' secured with cam member 3 to the magneto frame A by means of screws 4 (see'Fig'. 2). A rotatable driven mem er 5, of di k. f rm, pr vided with an apertured bearing hub 6, is secured to the armature shaft B by the key 7. 'As shown in the drawing, the aperture of the driven member 5 and a portion of. the aperture of its bearing hub 6, are tapered to fit over the correspondingly tapered portion 6 of the shaftB. A spanner lock nut 8, provided with a hub 9, is interiorly screw threaded for engagement with the threaded end 6' of the shaft, thediameter of the nut being greater than the diameter of the end of thehub bearing 6 so as to have overlapping engagement with the driving member 10. The nut Sbeing thus locked by the screw threads onto the armatureshaft and the driven member 5 and its hub 6 beingkeyed to said shaft, said three parts rotate together and at the same time the nut 8 bearing against the face of the driving member 10 holds the latter in place. 'In practice, I recommend a small clearance, say .005 of-an inch between the end of the hub 6 and the shown in Fig. 4; #Driving member 10 is pro vided with ahub 13journalled onhub 6 of driven member 5. Driving member 10 carries stud. 14 extending towardthe magneto and spaced from a stud-17 extending from the magneto and supp'orted-by the driven member 5.

Within the annular space enclosed by members 5 and 10' is located a volute spring 15 having one end 15 formedlto an age the studs 14 and 17 and the other en I 15"v attached to a spring support 16 having a portion 16 arranged to engage studs 14 and 17, so that in effect portion 16 is a continuation of spring 15. Support 16 is loosely. journaled-on hubs 6 and 13 and is provided with an aperture 16" through-which the spring 15 is threaded. When the spring 15 is in the position shown in Fig. 6 it is in' an initial state of stress, themembers 15 and 16 pushing in opposite directions against studs 14 and 17.

On that side of the driven member or disk 5, oppositethat carrying the stud 17, aretwo studsjor pins18, 18. Each of said pins affords a rpivotal bearing'support for a looking pawl "19, suitabl apertured to fit over said pin. 'Each paw "19, at its outer end, is,

' provided with a lug 20, adapted to engage the cam 3. The cam 3 is provided on its peri-Eheral margin with a cutaway portion 21 ich terminates ina cam-shoulder 22. The

lug 20 of the :pawl is adapted, at certain periods in the movement hereinfter described,

' to fall into the cut-away portion 21 and to with the effect of caus'in inmate is rotated thereby through couplings D D's As member 10 rotates stud 14 presses against portion 1.6 of spring. support 16 and motion is transmitted through spring 15 to stud L7 causing driven member 5 to rotate clockwise. The driving and driven members will be simultaneously'rotated, until the outer end 20.

of one of the awls 19, swinging upon its stud 18, dropsinto the cut-away space 21 of thefixed cam Sand comes into contact with the cam shoulder 22. When the lug 20 is thus engaging the non-rotatable cam shoulder '22, and the driven member 5' is thus arrested, the rotary forward movement of the driving member 10 continues, though momentarily retarded in its speed by the 'resisting action of the spring 15. when stressed in. addition to its initialstress. The continued rotation of the driving member '10, however, premntly brings one of the arms 25 of the yoke 23 into a position when the pawl 19 is lifted by said arm from the camshoulder 22. Ther'eupon the spring 15 will immediately, expand into its normal position 7 the momentarily retarded but now'release driven member 5 to again move forward in its path of -rotation, andwith an accelerated motiomas compared with the speed of rotation of the driving member 10; and thus, so to speak, catch upwith the'drivingmember 10.

:This momentaryretarding of area for example. of 32 degrees. Thus the current .flow or spark isproduced' at the proper and predetermined moment of-time;

my invention is as fol- I the fdi ward movement ofthe driven member 5 continues while the driving member 10 travels over an A similar action takes place with respect to the second pawl 19, as therevolution of the drivingmember 10 continues. It will be understood that while the driving 1nember 10. is making one complete revolution,-

the retarding, and then the accelerated forward movement of the'driven. memberv and the magneto. shaft will take place twice. There are thusproduced two impulses for each single revolution oftheshaft, corresponding to the two explosion strokes of a four cylinder engine.

When the driven-member 5. is released in the manner described the spring 15 delivers its stored energy tomember 5. and-to the magneto rotor connected therewith causing these parts .to rotate with a speed higher than the speed of shaft C during the engine starting operation. These .driven parts will strike ag'ainst stud 14, and the energy of rotation of said driven parts will be taken up in the spring as it is again stressed beyond normal when stud 17 tends to run ahead of stud 14. In this manner spring 15 acts as a shock absorbing or en ergy absorbing spring during the time the motion of the driven parts is approach ing in value the speed of the shaft C. It is apparent that in effect both ends of spring 15 transmit pressure to the studs 14 and 17. When spring 15 is being stressed above normal in winding it up for impulsing the magneto shaft; stud 14 moves ahead of stud 17 and parts 15 andtlti separate. Then when the driven parts are-released stud 17 runs ahead'of the stud 14 and parts 15 and 16 are again separated. In this way,

the one volute spring 15 acts as an impulse spring and as a cushioning spring .to 'relieve'. the armature rotor of stresses resulting from the retarding of its movement after the impulse.

Another of the advantages resulting from the-present invention is that the spring 15 may function with very little resistance due to friction. The spring itself is not engaged by the walls of its enclosure, and the only friction present is slight friction between spring support 16 and the hubs 6 and 13.

Obviously when the engine becomes selfoperative-and thespeed of shaft C exceeds a certain amount, the pawls 19 will be held away from the cam 3 by centrifugal force and the device will no longer operate as an impulse coupling.

IVhile the form of mechanism herem shown and described constitutes a preferred form of embodiment of the invention, it is to be nnderstood'that other forms might be adopted, all coming within the scope of the claims which follow.

What I claim is as follows 1. In an, impulsecoupling, the combination with driving and driven members; of

means for temporarily retarding then releasing said driven member; a volute spring for effecting an operative connection between said driving and driven members;

studs carried by saiddriving and driven members, respectively: and devices for causing said studs to receive pressure from either of the ends of said spring, including a part attached to the inner end of said spring and adapted to engage said studs.

2. In an impulse coupling, the combination with drivingand driven members one of which is provided with a hub; studs carried by said driving and driven members,

respectively of means fortemporarilyretarding then releasing said driven member; a volute spring for effecting an operative connection between said driving and driven members; a spring support loosely journalled upon said hub having a part extending outwardly to engage said studs and attached to the inner end of said spring;

and means for causing said studs to receive pressure from the outer end ofsaid spring.

3. In an impulse coupling, the combination with driving and driven members; of means for temporarily retarding then releasing said drivenmember; a volute spring for effecting an operative connection between said driving and driven members;

studs carried by said driving and driven members, respectively; a spring support rotatably mounted coaxially with said members and attached to the inner end ofsaid spring and having a part extending outwardly and apertured to receive the turnsof the spring; and means for causing said studs to receive pressure from the outer end of said spring.

4. In an impulse coupling, the combination with driving and driven members; of means for temporarily retarding then releasing said driven member; half, circular studs located with their flat, parallel faces adjacent, carried by said driving and driven members,respectivelyi a spring support rotatablyv mounted coaxially with said members, said support having an outwardly ex tending portion adapted to bear against said studs; and a v'olute spring having its outer end adapted to bear against said studs and its inner end attached to said spring support.

5. In an impulse coupling, the combina tion withsdriving and driven members; of

means for, temporarily retarding then reend adapted to bear against said studs and its inner end attached to said spring support. y

In testimony whereof I hereto allix my signature.

- RONALD K. EVANS. Witnesses VVM'. O. NELSON, KATHARINE WEAVER.

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